dotnet · jonpryor · Nov 16, 2021 · Nov 12, 2021
diff --git a/src/Xamarin.Android.Tools.Bytecode/Annotation.cs b/src/Xamarin.Android.Tools.Bytecode/Annotation.cs
@@ -12,8 +12,8 @@ public sealed class Annotation
 		ushort typeIndex;
 		public string Type => ((ConstantPoolUtf8Item) ConstantPool [typeIndex]).Value;
 
-		public IList<KeyValuePair<string, AnnotationElementValue>>
-			Values { get; } = new List<KeyValuePair<string, AnnotationElementValue>> ();
+		public IList<KeyValuePair<string, AnnotationElementValue?>>
+			Values { get; } = new List<KeyValuePair<string, AnnotationElementValue?>> ();
 
 		public Annotation (ConstantPool constantPool, Stream stream)
 		{
@@ -25,7 +25,7 @@ public Annotation (ConstantPool constantPool, Stream stream)
 				var elementNameIndex = stream.ReadNetworkUInt16 ();
 				var elementName = ((ConstantPoolUtf8Item) ConstantPool [elementNameIndex]).Value;
 				var elementValue = AnnotationElementValue.Create (constantPool, stream);
-				Values.Add (new KeyValuePair<string, AnnotationElementValue> (elementName, elementValue));
+				Values.Add (new KeyValuePair<string, AnnotationElementValue?> (elementName, elementValue));
 			}
 		}
 
@@ -42,7 +42,7 @@ public override string ToString ()
 			values.Append ("}");
 			return $"Annotation('{Type}', {values})";
 
-			void Append (KeyValuePair<string, AnnotationElementValue> value)
+			void Append (KeyValuePair<string, AnnotationElementValue?> value)
 			{
 				values.Append (value.Key).Append (": ");
 				values.Append (value.Value);

diff --git a/src/Xamarin.Android.Tools.Bytecode/AnnotationElementValue.cs b/src/Xamarin.Android.Tools.Bytecode/AnnotationElementValue.cs
@@ -9,9 +9,9 @@ namespace Xamarin.Android.Tools.Bytecode
 	// https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.7.16.1
 	public abstract class AnnotationElementValue
 	{
-		public virtual string ToEncodedString () => ToString ();
+		public virtual string? ToEncodedString () => ToString ();
 
-		public static AnnotationElementValue Create (ConstantPool constantPool, Stream stream)
+		public static AnnotationElementValue? Create (ConstantPool constantPool, Stream stream)
 		{
 			var tag = stream.ReadNetworkByte ();
 
@@ -38,8 +38,12 @@ public static AnnotationElementValue Create (ConstantPool constantPool, Stream s
 
 						var values = new List<AnnotationElementValue> ();
 
-						for (var i = 0; i < numValues; i++)
-							values.Add (Create (constantPool, stream));
+						for (var i = 0; i < numValues; i++) {
+							var v = Create (constantPool, stream);
+							if (v == null)
+								continue;
+							values.Add (v);
+						}
 
 						return new AnnotationElementArray { Values = values.ToArray () };
 					}
@@ -79,49 +83,53 @@ public static AnnotationElementValue Create (ConstantPool constantPool, Stream s
 
 	public class AnnotationElementEnum : AnnotationElementValue
 	{
-		public string TypeName { get; set; }
-		public string ConstantName { get; set; }
+		public string? TypeName { get; set; }
+		public string? ConstantName { get; set; }
 
 		public override string ToString () => $"Enum({TypeName}.{ConstantName})";
 	}
 
 	public class AnnotationElementClassInfo : AnnotationElementValue
 	{
-		public string ClassInfo { get; set; }
+		public string? ClassInfo { get; set; }
 
-		public override string ToString () => ClassInfo;
+		public override string? ToString () => ClassInfo;
 	}
 
 	public class AnnotationElementAnnotation : AnnotationElementValue
 	{
-		public Annotation Annotation { get; set; }
+		public Annotation? Annotation { get; set; }
 
-		public override string ToString () => Annotation.ToString ();
+		public override string? ToString () => Annotation?.ToString ();
 	}
 
 	public class AnnotationElementArray : AnnotationElementValue
 	{
-		public AnnotationElementValue[] Values { get; set; }
+		public AnnotationElementValue[]? Values { get; set; }
 
-		public override string ToString () => $"[{string.Join (", ", Values.Select (v => v.ToString ()))}]";
+		public override string ToString () => Values == null
+			? "[]"
+			: $"[{string.Join (", ", Values.Select (v => v.ToString ()))}]";
 
-		public override string ToEncodedString () => $"[{string.Join (", ", Values.Select (v => v.ToEncodedString ()))}]";
+		public override string? ToEncodedString () => Values == null
+			? "[]"
+			: $"[{string.Join (", ", Values.Select (v => v.ToEncodedString ()))}]";
 	}
 
 	public class AnnotationElementConstant : AnnotationElementValue
 	{
-		public string Value { get; set; }
+		public string? Value { get; set; }
 
-		public override string ToString () => Value;
+		public override string? ToString () => Value;
 	}
 
 	public class AnnotationStringElementConstant : AnnotationElementConstant
 	{
 		public override string ToString () => $"\"{Value}\"";
 
-		public override string ToEncodedString ()
+		public override string? ToEncodedString ()
 		{
-			return $"\"{Convert.ToBase64String (Encoding.UTF8.GetBytes (Value))}\"";
+			return $"\"{Convert.ToBase64String (Encoding.UTF8.GetBytes (Value ?? ""))}\"";
 		}
 	}
 }
diff --git a/src/Xamarin.Android.Tools.Bytecode/AttributeInfo.cs b/src/Xamarin.Android.Tools.Bytecode/AttributeInfo.cs
@@ -26,10 +26,10 @@ public IEnumerable<AttributeInfo> GetInfos (string name)
 			return this.Where (a => a.Name == name);
 		}
 
-		public T Get<T> ()
+		public T? Get<T> ()
 			where T : AttributeInfo
 		{
-			return (T) GetInfos (AttributeInfo.GetAttributeName<T>()).SingleOrDefault ();
+			return (T?) GetInfos (AttributeInfo.GetAttributeName<T>()).SingleOrDefault ();
 		}
 	}
 
@@ -88,7 +88,7 @@ public string Name {
 
 		internal static string GetAttributeName<T>()
 		{
-			string value;
+			string? value;
 			if (AttributeNames.TryGetValue (typeof(T), out value)) {
 				return value;
 			}
@@ -244,7 +244,7 @@ public ConstantPoolClassItem            Class {
 			get {return (ConstantPoolClassItem) ConstantPool [classIndex];}
 		}
 
-		public ConstantPoolNameAndTypeItem      Method {
+		public ConstantPoolNameAndTypeItem?     Method {
 			get {return methodIndex == 0 ? null : (ConstantPoolNameAndTypeItem) ConstantPool [methodIndex];}
 		}
 
@@ -351,7 +351,7 @@ public ConstantPoolClassItem OuterClass {
 			get {return (ConstantPoolClassItem) ConstantPool [outerClassInfoIndex];}
 		}
 
-		public string InnerName {
+		public string? InnerName {
 			get {
 				if (innerNameIndex == 0)
 					// anonymous class
@@ -360,7 +360,7 @@ public string InnerName {
 			}
 		}
 
-		public string OuterClassName => OuterClass?.Name?.Value;
+		public string? OuterClassName => OuterClass?.Name?.Value;
 
 		public override string ToString ()
 		{
@@ -447,7 +447,7 @@ public MethodParameterInfo (ConstantPool constantPool)
 			ConstantPool    = constantPool;
 		}
 
-		public string Name {
+		public string? Name {
 			get {
 				if (nameIndex == 0)
 					return null;

diff --git a/src/Xamarin.Android.Tools.Bytecode/ClassFile.cs b/src/Xamarin.Android.Tools.Bytecode/ClassFile.cs
@@ -2,6 +2,7 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 
@@ -23,7 +24,7 @@ public sealed class ClassFile {
 		public Methods              Methods;
 		public AttributeCollection  Attributes;
 
-		ClassSignature              signature;
+		ClassSignature?             signature;
 
 
 		public ClassFile (Stream stream)
@@ -100,14 +101,17 @@ public string PackageName {
 
 		public string FullJniName => "L" + ThisClass.Name.Value + ";";
 
-		public string SourceFileName {
+		public string? SourceFileName {
 			get {
 				var sourceFile  = Attributes.Get<SourceFileAttribute> ();
 				return sourceFile == null ? null : sourceFile.FileName;
 			}
 		}
 
-		public bool TryGetEnclosingMethodInfo (out string declaringClass, out string declaringMethod, out string declaringDescriptor)
+		public bool TryGetEnclosingMethodInfo (
+				[NotNullWhen (true)] out string? declaringClass,
+				out string? declaringMethod,
+				out string? declaringDescriptor)
 		{
 			declaringClass = declaringMethod = declaringDescriptor = null;
 
@@ -122,7 +126,7 @@ public bool TryGetEnclosingMethodInfo (out string declaringClass, out string dec
 			return true;
 		}
 
-		public ClassSignature GetSignature ()
+		public ClassSignature? GetSignature ()
 		{
 			if (this.signature != null)
 				return this.signature;
@@ -161,7 +165,7 @@ public IList<InnerClassInfo> InnerClasses {
 			}
 		}
 
-		public InnerClassInfo InnerClass {
+		public InnerClassInfo? InnerClass {
 			get {
 				return InnerClasses.SingleOrDefault (c => c.InnerClass == ThisClass);
 			}
@@ -189,7 +193,7 @@ public bool IsEnum {
 			get {return (AccessFlags & ClassAccessFlags.Enum) != 0;}
 		}
 
-		public override string ToString () => ThisClass?.Name.Value;
+		public override string? ToString () => ThisClass?.Name.Value;
 	}
 
 	[Flags]

diff --git a/src/Xamarin.Android.Tools.Bytecode/ClassPath.cs b/src/Xamarin.Android.Tools.Bytecode/ClassPath.cs
@@ -25,17 +25,17 @@ public class ClassPath {
 
 		IList<ClassFile> classFiles = new List<ClassFile> ();
 
-		public string ApiSource { get; set; }
+		public string? ApiSource { get; set; }
 
-		public IEnumerable<string> DocumentationPaths { get; set; }
+		public IEnumerable<string>? DocumentationPaths { get; set; }
 
-		public string AndroidFrameworkPlatform { get; set; }
+		public string? AndroidFrameworkPlatform { get; set; }
 
 		public bool AutoRename { get; set; }
 
-		public ClassPath (string path = null)
+		public ClassPath (string? path = null)
 		{
-			if (string.IsNullOrEmpty (path))
+			if (path == null || string.IsNullOrEmpty (path))
 				return;
 
 			Load (path);
@@ -138,14 +138,14 @@ public static bool IsJmodFile (string jmodFile)
 			}
 		}
 
-		XAttribute GetApiSource ()
+		XAttribute? GetApiSource ()
 		{
 			if (string.IsNullOrEmpty (ApiSource))
 				return null;
 			return new XAttribute ("api-source", ApiSource);
 		}
 
-		XAttribute GetPlatform ()
+		XAttribute? GetPlatform ()
 		{
 			if (string.IsNullOrEmpty (AndroidFrameworkPlatform))
 				return null;
@@ -286,20 +286,27 @@ void FixupParametersFromDocs (XElement api, string path)
 			var elements = api.XPathSelectElements ("./package/class[@visibility = 'public' or @visibility = 'protected']").ToList ();
 			elements.AddRange (api.XPathSelectElements ("./package/interface[@visibility = 'public' or @visibility = 'protected']"));
 			foreach (var elem in elements) {
-				var currentpackage = elem.Parent.Attribute ("name").Value;
-				var className = elem.Attribute ("name").Value;
+				var currentpackage = elem.Parent?.Attribute ("name")?.Value ?? "";
+				var className = elem.Attribute ("name")?.Value;
+
+				if (className == null)
+					continue;
 
 				var methodsAndConstructors = elem.XPathSelectElements ("./method[@visibility = 'public' or @visibility = 'protected']").ToList ();
 				methodsAndConstructors.AddRange (elem.XPathSelectElements ("./constructor[@visibility = 'public' or @visibility = 'protected']"));
 
 				foreach (var method in methodsAndConstructors) {
-					var currentMethod = method.Attribute ("name").Value;
+					var currentMethod = method.Attribute ("name")?.Value;
+					if (currentMethod == null)
+						continue;
 
 					var parameterElements = method.Elements ("parameter").ToList ();
-					if (!parameterElements.Select (x => x.Attribute ("name").Value).Any (p => IsGeneratedName (p)))
+					if (!parameterElements.Select (x => x.Attribute ("name")?.Value).Any (p => p != null && IsGeneratedName (p)))
 						continue;
 
-					var parameters = parameterElements.Select (p => p.Attribute ("type").Value);
+					var parameters = parameterElements
+						.Select (p => p.Attribute ("type")?.Value!)
+						.Where (p => p != null);
 
 					if (!parameters.Any ())
 						continue;
@@ -308,7 +315,10 @@ void FixupParametersFromDocs (XElement api, string path)
 					if (pnames == null || pnames.Length != parameterElements.Count)
 						continue;
 					for (int i = 0; i < parameterElements.Count; i++) {
-						parameterElements [i].Attribute ("name").Value = pnames [i];
+						var a = parameterElements [i].Attribute ("name");
+						if (a == null)
+							continue;
+						a.Value = pnames [i];
 					}
 				}
 			}

diff --git a/src/Xamarin.Android.Tools.Bytecode/ConstantPool.cs b/src/Xamarin.Android.Tools.Bytecode/ConstantPool.cs
@@ -18,7 +18,7 @@ public ConstantPool (Stream stream)
 
 			// indexes are one-based;
 			// "The constant_pool table is indexed from 1 to constant_pool_count-1."
-			Add (null);
+			Add (null!);
 			int constant_pool_count = stream.ReadNetworkUInt16 ();
 			for (int i = 1; i < constant_pool_count; ++i) {
 				var entry   = ConstantPoolItem.CreateFromStream (this, stream);

diff --git a/src/Xamarin.Android.Tools.Bytecode/Fields.cs b/src/Xamarin.Android.Tools.Bytecode/Fields.cs
@@ -33,7 +33,7 @@ public sealed class FieldInfo {
 		public  ConstantPool        ConstantPool    {get; private set;}
 		public  FieldAccessFlags    AccessFlags     {get; private set;}
 		public  AttributeCollection Attributes      {get; private set;}
-		public  string              KotlinType      { get; set; }
+		public  string?             KotlinType      {get; set;}
 
 		public FieldInfo (ConstantPool constantPool, Stream stream)
 		{
@@ -56,7 +56,7 @@ public  string Descriptor {
 			}
 		}
 
-		public string GetSignature ()
+		public string? GetSignature ()
 		{
 			var signature   = Attributes.Get<SignatureAttribute> ();
 			return signature != null ? signature.Value : null;